Paint bucket
Tap a place and get it all flooded by a single color!
Settings
Contiguous
If set to "No", will ignore all boundaries and edges, painting every color that is the same as the one you touched, no matter where it is, i.e. you turn it into a "replace color".
Apply pattern
Instead of solid colors, will fill a pattern!
Invert pattern
What is transparent will be coloured and vice-versa.